diff --git a/test/functional/feature_block.py b/test/functional/feature_block.py
--- a/test/functional/feature_block.py
+++ b/test/functional/feature_block.py
@@ -57,7 +57,7 @@
 
     def serialize(self):
         r = b""
-        r += super(CBlock, self).serialize()
+        r += super().serialize()
         r += struct.pack("<BQ", 255, len(self.vtx))
         for tx in self.vtx:
             r += tx.serialize()
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -520,16 +520,16 @@
     __slots__ = ("vtx",)
 
     def __init__(self, header=None):
-        super(CBlock, self).__init__(header)
+        super().__init__(header)
         self.vtx = []
 
     def deserialize(self, f):
-        super(CBlock, self).deserialize(f)
+        super().deserialize(f)
         self.vtx = deser_vector(f, CTransaction)
 
     def serialize(self):
         r = b""
-        r += super(CBlock, self).serialize()
+        r += super().serialize()
         r += ser_vector(self.vtx)
         return r
 
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -109,7 +109,7 @@
             return _opcode_instances[n]
         except IndexError:
             assert len(_opcode_instances) == n
-            _opcode_instances.append(super(CScriptOp, cls).__new__(cls, n))
+            _opcode_instances.append(super().__new__(cls, n))
             return _opcode_instances[n]
 
 
@@ -401,7 +401,7 @@
 
     def __init__(self, msg, data):
         self.data = data
-        super(CScriptTruncatedPushDataError, self).__init__(msg)
+        super().__init__(msg)
 
 
 # This is used, eg, for blockchain heights in coinbase scripts (bip34)
@@ -487,14 +487,14 @@
 
     def __new__(cls, value=b''):
         if isinstance(value, bytes) or isinstance(value, bytearray):
-            return super(CScript, cls).__new__(cls, value)
+            return super().__new__(cls, value)
         else:
             def coerce_iterable(iterable):
                 for instance in iterable:
                     yield cls.__coerce_instance(instance)
             # Annoyingly on both python2 and python3 bytes.join() always
             # returns a bytes instance even when subclassed.
-            return super(CScript, cls).__new__(
+            return super().__new__(
                 cls, b''.join(coerce_iterable(value)))
 
     def raw_iter(self):
diff --git a/test/functional/wallet_txn_clone.py b/test/functional/wallet_txn_clone.py
--- a/test/functional/wallet_txn_clone.py
+++ b/test/functional/wallet_txn_clone.py
@@ -29,7 +29,7 @@
 
     def setup_network(self):
         # Start with split network:
-        super(TxnMallTest, self).setup_network()
+        super().setup_network()
         disconnect_nodes(self.nodes[1], self.nodes[2])
         disconnect_nodes(self.nodes[2], self.nodes[1])